Systems and methods for tagging and acoustically characterizing containers

ABSTRACT

Embodiments of the present invention provide systems and methods for tagging and acoustically characterizing containers.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional PatentApplication No. 62/240,412, filed Oct. 12, 2015 and entitled “Systemsand Methods for Tagging and Acoustically Characterizing Containers,” theentire contents of which are incorporated by reference herein.

FIELD

This application relates to tagging containers, such as containersformed using injection molding. But it will be appreciated that theinvention has a much broader range of applicability.

BACKGROUND

Injection molding is a ubiquitous, high-throughput manufacturingprocess, whereby parts can be molded at substantial scale whileextending design and functional consistency across many parts. Theinjection molding process consists of a mold with one or more cavitiesthat contains the shape, geometry, and design features for the part; a“gate” that allows for the molten plastic to be injected into individualcavities within the mold; ejection pins to allow for removal of the partfrom the mold; and various processing parameters such as holding time,temperature, melt mass-flow rate, packing pressure, etc. that affect theconformation and solidification of the molten plastic within the mold.In order to increase the speed, scale, and efficiency at which parts canbe molded, manufacturers often employ multi-cavity molds, where eachcavity replicates the part such that multiple parts can be generated permolding cycle.

SUMMARY

This application relates to tagging containers, such as containersformed using injection molding. These tags can be associated withinformation used to identify the origin of the container and associated,retrievable predetermined physical properties useful in both acousticauditing of the container contents and ejection of materials from thecontainer by acoustic droplet ejection (ADE). But it will be appreciatedthat the invention has a much broader range of applicability.

Under one aspect, a container configured to hold a fluid includes atleast one vertical sidewall; and a bottom coupled to the at least onevertical sidewall, the bottom being configured to receive an acousticsignal, the bottom including a plurality of recesses, grooves, orprotrusions thereon or therein so as to provide a plurality of times offlight of the acoustic signal through the bottom.

In some embodiments, a first subset of the plurality of recesses,grooves, or protrusions includes a first depth providing a first time offlight of the acoustic signal, and a second subset of the plurality ofrecesses, grooves or protrusions includes a second depth providing asecond time of flight of the acoustic signal, the first depth beingdifferent from the second depth.

In some embodiments, a first one of the plurality of recesses, grooves,or protrusions includes a different length, aspect ratio, or depth thana second one of the plurality of recesses, grooves, or protrusions.

In some embodiments, the plurality of recesses, grooves, or protrusionsinclude a hydrophobic region configured so as to increase or decreasethe amplitude of reflection of the acoustic signal. For example, in someembodiments, the plurality of recesses, grooves, or protrusions includea hydrophobic micropillar array.

In some embodiments, the plurality of recesses, grooves, or protrusionsare configured so as to be located outside of an acoustic path betweenthe fluid and an acoustic transducer generating the acoustic signal. Insome embodiments, the plurality of recesses, grooves, or protrusions areconfigured so as to be located along and within an acoustic path betweenthe fluid and an acoustic transducer generating the acoustic signal.

In some embodiments, the container includes a multiwell plate, avertical sidewall of the at least one vertical sidewall and the bottomcorresponding to a single well of the multiwall plate.

In some embodiments, the sidewall and the bottom include a plastic. Insome embodiments, the plastic is selected from the group consisting ofcyclic olefin polymer, cyclic olefin copolymer, polypropylene, andpolystyrene.

Under another aspect, a container configured to hold a fluid includes atleast one vertical sidewall; and a bottom coupled to the at least onevertical sidewall, the bottom being configured to receive an acousticsignal, the bottom including a thickness selected such that thecontainer is identifiable based on a time of flight of the acousticsignal through the bottom.

Under yet another aspect, a method of characterizing a containerconfigured to hold a fluid includes providing the container. Thecontainer can include at least one vertical sidewall; and a bottomcoupled to the at least one vertical sidewall, the bottom beingconfigured to receive an acoustic signal, the bottom including aplurality of recesses, grooves, or protrusions thereon or therein. Themethod can include transmitting an acoustic signal through the bottom,the plurality of recesses, grooves, or protrusions providing a pluralityof times of flight of the acoustic signal through the bottom. The methodalso can include receiving a reflection of the transmitted acousticsignal; and characterizing an acoustic impedance of the container basedon the reflection.

In some embodiments, the method includes retrieving from acomputer-readable medium a value characterizing a thickness of thebottom based on the reflection. The characterizing the acousticimpedance of the container can be based on the retrieved valuecharacterizing the thickness of the bottom.

In some embodiments, a first subset of the plurality of recesses,grooves, or protrusions includes a first depth providing a first time offlight of the acoustic signal, and a second subset of the plurality ofrecesses, grooves or protrusions includes a second depth providing asecond time of flight of the acoustic signal, the first depth beingdifferent from the second depth.

In some embodiments, a first one of the plurality of recesses, grooves,or protrusions includes a different length, aspect ratio, or depth thana second one of the plurality of recesses, grooves, or protrusions.

In some embodiments, the plurality of recesses, grooves, or protrusionsinclude a hydrophobic region configured so as to increase reflection ofthe acoustic signal. For example, in some embodiments, the plurality ofrecesses, grooves, or protrusions include a hydrophobic micropillararray.

In some embodiments, the plurality of recesses, grooves, or protrusionsare located outside of an acoustic path between the fluid and anacoustic transducer generating the acoustic signal. In some embodiments,the plurality of recesses, grooves, or protrusions are located along andwithin an acoustic path between the fluid and an acoustic transducergenerating the acoustic signal.

In some embodiments, the container includes a multiwell plate, and avertical sidewall of the at least one vertical sidewall and the bottomcorrespond to a single well of the multiwall plate.

In some embodiments, the sidewall and the bottom include a plastic. Insome embodiments, the plastic is selected from the group consisting ofcyclic olefin polymer, cyclic olefin copolymer, polypropylene, andpolystyrene.

Under another aspect, a method of characterizing a container configuredto hold a fluid includes providing the container. The container caninclude at least one vertical sidewall; and a bottom coupled to the atleast one vertical sidewall, the bottom being configured to receive anacoustic signal, the bottom including a thickness. The method caninclude receiving a reflection of the transmitted acoustic signal, thereflection having a time of flight through the thickness; identifyingthe container based on the time of flight; and characterizing anacoustic impedance of the container based on the identification.

Under still another aspect, a system for characterizing a containerconfigured to hold a fluid includes the container. The container caninclude at least one vertical sidewall; and a bottom coupled to the atleast one vertical sidewall, the bottom being configured to receive anacoustic signal, the bottom including a plurality of recesses, grooves,or protrusions thereon or therein. The system also can include anacoustic transducer configured so as to transmit an acoustic signalthrough the bottom, the plurality of recesses, grooves, or protrusionsproviding a plurality of times of flight of the acoustic signal throughthe bottom. The acoustic transducer further can be configured so as toreceive a reflection of the transmitted acoustic signal. The systemfurther can include a controller configured so as to characterize anacoustic impedance of the container based on the reflection.

In some embodiments, the system further includes a computer-readablemedium. The controller can be configured so as to: retrieve from thecomputer-readable medium a value characterizing a thickness of thebottom based on the reflection; and characterize the acoustic impedanceof the container based on the value characterizing the thickness of thebottom.

In some embodiments, a first subset of the plurality of recesses,grooves, or protrusions includes a first depth providing a first time offlight of the acoustic signal, and a second subset of the plurality ofrecesses, grooves or protrusions includes a second depth providing asecond time of flight of the acoustic signal, the first depth beingdifferent from the second depth.

In some embodiments, a first one of the plurality of recesses, grooves,or protrusions includes a different length, aspect ratio, or depth thana second one of the plurality of recesses, grooves, or protrusions.

In some embodiments, the plurality of recesses, grooves, or protrusionsinclude a hydrophobic region configured so as to increase reflection ofthe acoustic signal. For example, in some embodiments, the plurality ofrecesses, grooves, or protrusions include a hydrophobic micropillararray.

In some embodiments, the plurality of recesses, grooves, or protrusionsare located outside of an acoustic path between the fluid and anacoustic transducer generating the acoustic signal. In some embodiments,the plurality of recesses, grooves, or protrusions are located along andwithin an acoustic path between the fluid and an acoustic transducergenerating the acoustic signal.

In some embodiments, the container includes a multiwell plate, avertical sidewall of the at least one vertical sidewall and the bottomcorresponding to a single well of the multiwall plate.

In some embodiments, the sidewall and the bottom include a plastic. Insome embodiments, the plastic can be selected from the group consistingof cyclic olefin polymer, cyclic olefin copolymer, polypropylene, andpolystyrene.

Under yet another aspect, a system for characterizing a containerconfigured to hold a fluid includes the container. The container caninclude at least one vertical sidewall; and a bottom coupled to the atleast one vertical sidewall, the bottom being configured to receive anacoustic signal, the bottom including a thickness. The system caninclude an acoustic transducer configured so as to transmit an acousticsignal through the bottom. The acoustic transducer further can beconfigured so as to receive a reflection of the transmitted acousticsignal, the reflection having a time of flight through the thickness.The system further can include a controller configured so as to:identify the container based on the time of flight; and characterize anacoustic impedance of the container based on the identification.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 schematically illustrates an arrangement including a containerand a fluid therein coupled to an acoustic transducer with predeterminedproperties and in which the acoustic impedance of the fluid and thecontainer bottom are unknown.

FIG. 2 schematically illustrates exemplary steps for acousticallycharacterizing a tagged container and a fluid therein, according to someembodiments of the present invention.

FIG. 3 schematically illustrates exemplary features that can be providedin a container so as to tag that container and acoustically characterizethe container, according to some embodiments of the present invention.

FIG. 4 schematically illustrates exemplary features that can be providedin a container so as to tag that container and acoustically characterizethe container, according to some embodiments of the present invention.

FIG. 5 schematically illustrates exemplary features that can be providedin a container so as to tag that container and acoustically characterizethe container, according to some embodiments of the present invention.

FIG. 6 schematically illustrates exemplary features that can be providedin a container so as to tag that container and acoustically characterizethe container, according to some embodiments of the present invention.

FIG. 7 schematically illustrates exemplary features that can be providedin a container so as to tag that container and acoustically characterizethe container, according to some embodiments of the present invention.

DETAILED DESCRIPTION

This application relates to tagging containers, such as containersformed using injection molding. But it will be appreciated that theinvention has a much broader range of applicability.

For example, an injection mold can include multiple cavities to make the“same” part as one another. However, one concern regarding such amulti-cavity approach as it relates to acoustic liquid handling is thatvariations in the acoustic properties can exist from one container orcavity as compared to another container or cavity (or even within onecavity or container), which can affect the acoustic characterization ofthat container, a liquid within that container, and acoustic transfer ofthat liquid from that container. In such cases, an assumption may not bevalid that each part made from the mold, whether it is one cavity ormulti-cavity, has similar part molding and solidification dynamics suchthat they can be assumed to be the same and thus are acousticallyindistinguishable from each other. Once the assumptions of the acousticproperties of the container, e.g., acoustic impedance, are no longervalid, the determination of the acoustic properties of the fluidtherein, e.g., acoustic impedance of that fluid, can become difficult orimpossible using previously available techniques, such as schematicallyillustrated in FIG. 1.

For example, FIG. 1 schematically illustrates an exemplary arrangementfor characterizing a container and a fluid therein. In FIG. 1, anacoustic transducer assembly 110 is coupled to the bottom of a container120 (e.g., a plastic container, such as a tube) via a coupling fluid130, and a fluid 140 is disposed within the container 140. An acousticsignal 111 is initiated from the transducer 110 and focused through thevarious intermediate materials to a spot at or near the fluid surface141. At each of the interfaces, e.g., between the coupling fluid 130 andthe bottom 122 of the container bottom 121 (BB), between the top 123 ofthe container bottom 121 (TB) and the fluid 140, and between the top 141of the fluid 140 and the air 142, parts 112 of the acoustic signal arereflected back to the transducer 110 and converted back into digitalinformation. The voltage that the acoustic signal 112 induces in thetransducer 110, the frequency content of the acoustic signal 112, andthe time after the initial acoustic signal 112 are recorded andsubsequently analyzed. However, analysis of the acoustic impedance ofthe fluid 140 (Z₄) cannot be determined accurately without sufficientknowledge of the acoustic impedance of the bottom 121 of the container(Z₃). The acoustic impedance of the transducer assembly 110 (Z₁) and ofthe coupling fluid 130 (Z₂) are both known. When the reliablemeasurement of the acoustic impedance of the fluid 140 is not possible,proper selection of the acoustic ejection parameters for transferringthe liquid 140—such as the focal point, frequency of the acoustic signal111, voltage delivered to the transducer 110, and the like—cannot beproperly selected from a lookup table or database.

Therefore, it is desirable to have an ability to identify and track fromwhere parts (such as containers), or features within a single part(e.g., container), originated within a mold (e.g., an injection mold forplastic) so as to facilitate monitoring and managing deviations inmolding dynamics. For example, the ability to track the molding locationcan facilitate establishment of the typical (e.g., average) acousticimpedance of parts coming from that location or mold, preserving theability to make assumptions about the plastic and enabling thesubsequent identification of customer fluids properties. It is desirablethat this information should also be accessible and amenable to rapid,unambiguous acoustic characterization during routine operation.

The systems and methods presented in this document are described in thecontext of an acoustic container that in some ways is similar to thatillustrated in FIG. 1, as this is a particularly useful example wherethe systems and methods can be used to properly audit the fluid andperform acoustic droplet ejection. However, the present systems andmethods are broadly applicable to parts having other form factors, e.g.,such as suitable for use in acoustic liquid handling, such as multi-wellplates or microfluidic consumable devices. In some embodiments, thepresent containers can be fabricated from a multi-cavity mold, andrandomly delivered to a liquid handler similar to that illustrated inFIG. 1. Therefore, so as to facilitate determining the acousticproperties of the container or part molded in each cavity, it is usefulto provide mold tracking features on or within each container or part sothe acoustic properties for parts from each cavity of the mold can beknown based on a previously measured or predetermined value. Suchtracking features can, in some embodiments, include geometric featuresthat are tooled into the mold itself so as to include specific taggingfeatures within all parts generated by that cavity without the need forfurther modification after being ejected from the mold. Alternatively,post-molding modifications can be made to all parts from a cavity of themold so as to enhance the ability to detect the molded-in taggingfeatures. Other exemplary embodiments can include distinct post-moldingmodifications of parts made from different cavities such that the partscan be modified based on their cavity of origin to produce theappropriate tag. Non-limiting examples of post-molding features include:a super-hydrophobic coating that is selectively patterned on the surfaceof the part that changes the reflected acoustic signals; laser bar codesthat selectively change the polymer structure to change the reflectedacoustic signals; etched or protruding microstructures fabricated in aconvenient location on the part; overmolding of various materials thatreflect varying amounts of acoustic signal; 3D printing of patterns; andthe like—with each pattern uniquely corresponding to the mold location.

For example, some embodiments of the present systems and methods can useunique tags (which also can be referred to as patterns or identifiers)that are introduced into the mold to identify from where the part (e.g.,if utilizing a multiple cavity mold for producing nominally identicalparts), or features within a part (e.g., one well in a multi-well plate,for example) originated within the mold. The tag can include a varietyof suitable features, e.g., one or more of the following four features,and optionally a combination of each of the following four features:

1) the features of the tag substantially do not disrupt the acousticcharacterization or droplet ejection (transfer) process;

2) the features of the tag uniquely identify the location of the moldwhere the part or feature was fabricated;

3) the features of the tag can be read using acoustic signals from atransducer and subsequently interpreted (e.g., the same transducer, butnot limited to the same transducer); and/or

4) the features of the tag are not detrimental to the normal operationof the liquid handler.

For example, FIG. 2 schematically illustrates exemplary steps foracoustically characterizing a tagged container 220 and a fluid 240therein, according to some embodiments of the present invention. Withthe introduction of mold identification features on each part, e.g.,container 220, calibration curves can be prepared that characterize theacoustic impedance (or potentially another acoustic property such assound speed) of each part, and assumptions can be made regarding theacoustic characteristics of the material from which the part is made.Such information can be used in a lookup table that was previouslydeveloped using the liquid handler, and the correct acoustic dropletejection parameters can be selected so as to achieve the desired dropletvolume of the fluid. The acoustic impedance of the fluid 240 can beparticularly useful as it can also can be used to report certaincharacteristics of the fluid, such as the concentration of certaincompounds, e.g., the percentage of dimethyl sulfoxide, glycerol, or thelike. For example, as illustrated in FIG. 2, the container 220 can becharacterized using the tag 250 embedded therein (mold/cavityidentifier), and acoustic impedance of the fluid 240 (Z₄) can bemeasured (step i), e.g., including generating an acoustic signal withtransducer 210, transmitting that signal to container 220 and fluid 240via coupling fluid 230, and receiving acoustic reflections at transducer210 via coupling fluid 230. Tag 250 can have any suitable configuration,including but not limited to any configuration described herein withreference to Exemplary Embodiments 1, 2, 3, 4, 5, 6, or 7, or suitablemodification thereof. Information about Z₄ then can be used with alookup table in a database that provides information for acousticdroplet ejection (ADE) based on the Z₄ measurement (step ii). The lookuptable can provide one or more of the following information, andoptionally a combination of all of the following information (step iii):fluid speed of sound, optimal acoustic signal parameters for ADE,acoustic focal point, and information about fluid properties. Any ofsuch information suitably can be used to perform ADE and optionally toreport fluid properties to a user, e.g., via a display coupled to theliquid handler.

For example, in one non-limiting embodiment, the present system caninclude the container (e.g., container 220), which includes at least onesidewall (e.g., sidewall 225) and a bottom (e.g., bottom 221), and aplurality of recesses, grooves, or protrusions (e.g., tag 250) includedon or within the bottom. The system also can include an acoustictransducer (e.g., transducer 210) configured so as to transmit anacoustic signal through the bottom, the plurality of recesses, grooves,or protrusions providing a plurality of times of flight and voltages ofthe acoustic signal through the bottom. The acoustic transducer furthercan be configured so as to receive a reflection of the transmittedacoustic signal. The system also can include a controller 260, such as acomputer and associated software algorithms, configured so as tocharacterize an acoustic impedance of the container based on thereflection, e.g., such as a computer including a processor 261 and anon-volatile computer readable medium 262, and associated softwarealgorithms stored on the computer readable medium, configured so as tocause the processor to characterize an acoustic impedance of thecontainer based on the reflection.

Note that in embodiments such as illustrated in FIG. 2 and elsewhereherein, any suitable portion of sidewall 225 can have any suitable anglerelative to bottom 221 so as to be considered “vertical.” For example,some or all of sidewall 225 can be considered to be “vertical” at arange of angles between about 10 degrees and 90 degrees relative tobottom 221. Additionally, different portions of sidewall 225 can havedifferent angles than one another relative to bottom 221. For example,in the nonlimiting embodiment illustrated in FIG. 2, a first (e.g.,lower) portion of sidewall 225 can have a first angle relative to bottom221, and a second (e.g., upper) portion of sidewall 225 can have asecond angle relative to bottom 221. Illustratively, the first angle canbe smaller than the second angle, or the first angle can be larger thanthe second angle. In one example, sidewall 225 can be arranged such thatone or both of the outer surface and the inner surface of container 220is generally conical. Such a configuration can, for example, reduce deadvolume within container 220 or facilitate liquid 240 to collect moreeasily at the bottom of container 220 with a greater depth.

In another example, a method of characterizing a container (e.g.,container 220) configured to hold a fluid (e.g., fluid 240) can includeproviding such a container; transmitting an acoustic signal through thebottom (e.g., bottom 221), the plurality of recesses, grooves, orprotrusions (e.g., tag 250) providing a plurality of times of flight ofthe acoustic signal through the bottom; receiving a reflection of thetransmitted acoustic signal; and characterizing an acoustic impedance ofthe container based on the reflection.

In some embodiments, the present tags (e.g., tag 250) can be implementedusing any suitable combination of a variety of design considerations,such as one or more of: managing the coupling fluid-plastic interactionby avoiding features that can get stuck on the part (e.g. sharp cornersthat would retain fluid and be difficult to remove with suction or avacuum dryer); disposing the features of the tag outside of the path ofthe acoustic signal during fluid characterization and ejection(transfer) steps; and/or utilizing tag features that are dimensionallycompatible with the dimensions of the part and can be resolved by theacoustic signal, e.g., with a wavelength generated by the sametransducer that is used to transfer as well as the transducer used forother acoustic transfer applications. For example, some transducers canhave characteristic wavelengths on the order of 250 μm and 125 μm, forthe transfer of 25 and 2.5 nL droplets, respectively. Acoustic signalsgenerally are understood to be able to resolve features whose lateraldimensions are approximately no smaller than half the wavelength of theacoustic signal; so in this non-limiting example, one or more featuresof the tag include a dimension that is at least about 125 μm for a 25 nLinstrument, or at least about 63 μm for a 2.5 nL instruments. In someembodiments, features of the tag are sufficiently spaced apart from oneanother such that they can be easily molded and resolved by an acoustictransducer, e.g., the same transducer used for acoustic droplet ejectioncould also be used to detect these features. Such design considerationscan extend to shorter and longer wavelength transducers and can beexpected to scale in a linear fashion. In some embodiments, thesensitivity of measurement based on the time of flight to the featuresof the tag can be finer than the half wavelength based upon the samplingfrequency of the measurement device connected to the acoustic receiversubstantially exceeding the frequency of the acoustic wave. For example,sampling 10 MHz acoustic signals reflected from half-wavelength featureswith 300 MHz or higher analog-to-digital resolution with a watercoupling fluid between the transducer and container feature can provide10 micron or less accuracy of the feature distance from the transducer.Raising acoustic frequency and time resolution of signal detection canimprove feature detection as well as other techniques known to those ofskill in the art of sonar and medical ultrasound.

Furthermore, the position of the transducer for focusing the acousticwave can impact the measurement time and resolving capability of thetransducer. For example, certain fluid characterization applications canbe performed without the transducer focused at the bottom of the fluidcontainer, which in some circumstances can result in lower resolution.In another example, the transducer can be lowered so as to focus theacoustic signal closer to the mold identification feature, so as toimprove the ability to resolve small features. This refocusing movementcan require tens or hundreds of milliseconds depending on the motionsystem and distance from audit position to feature detection position.In some embodiments, the features of the tag can be observedacoustically with no additional time required to perform themeasurement, in contrast to other methods such as a secondarytransducer, camera, or laser system that can require hundreds ofmilliseconds or more per measurement.

Additionally, the acoustic transducer can be configured so as to operatewith standard container materials and fluids that are commonly utilizedfor acoustic liquid handling in the life sciences. Exemplary plasticsthat suitably can be included in the present containers include, but arenot limited to, a plastic selected from the group consisting of: cyclicolefin polymer, cyclic olefin copolymer, polypropylene, and polystyrene.For example, a commonly used polymer such as polypropylene has anacoustic impedance value on the order of 2.5 MRayl; and fluids mostcommonly transferred in life sciences applications range from 0.8 to 2.4MRayl. The variation in the acoustic impedance of a polymer, such aspolypropylene, can vary in tenths of MRayl due to acoustic moldingprocesses. Therefore, the acoustic transducer can be configured so as toresolve differences in acoustic impedance between these materials onthis scale, using acoustic signal processing such as known to those ofskill in the art. Note that this example does not limit the presentsystems and methods to acoustic impedance of polypropylene, or theacoustic impedance of fluids described herein.

Such exemplary design considerations, and other design considerations,can be used in some embodiments of the present systems and methods. Forexample, practitioners of injection molding would understand the needfor draft angles to facilitate mold release for various plastics.

Various non-limiting embodiments, and various examples of designconsiderations that suitably can be implemented in such embodiments, nowwill be described.

In some embodiments, tags are provided for a tube and rack scheme, wheretubes are filled with customer fluids and placed within a rack(containing spaces for 96 tubes, in one non-limiting example). In suchembodiments, the tags (patterns) can be arranged so as to beconveniently readable by the acoustic beam, e.g., by not requiringalignment along a particular axis (one example described below withreference to exemplary embodiment 4), or by including alignment featuresat the tube-rack interface. For example, in some embodiments, the tags(unique identifying patterns) can be replicated at two or morepredetermined positions. One non-limiting embodiment can include tagsdisposed at the “3, 6, 9, and 12 o'clock” positions along the tubeperimeter (e.g., four-fold rotational, and x- and y-axis mirrorsymmetry), optionally with corresponding grooves in the rack so as tofacilitate proper placement. Such an arrangement can facilitate scanninga rack of tubes either horizontally or vertically and putting the tags(patterns) within the scan range of the acoustic beam. One non-limitingexample of such an embodiment includes four notches, but it should berecognized that the tags can be replicated n times along the perimeterand m notches, where n and m can be different integer values, can beprovided so as to facilitate proper alignment of the tags. If the numberof pattern replicates became high enough (high n), notches or alignmentpatterns may not necessarily be needed (e.g., complete rotationalsymmetry can be preserved).

The following descriptions assume proper alignment of the features, anddetail various non-limiting patterning and readout techniques that canbe used so as to achieve the desired function of identifying theoriginal mold location (or mold if more than one used to make the sameparts) for the part using acoustic signals.

Exemplary Embodiment 1: Dimples Representing 0/1's that are ReadAcoustically

One non-limiting approach to encoding information (a tag) uses binaryinformation so as to encode the location of the feature (e.g., well) orpart (e.g., cavity # within the mold. For example, FIG. 3 schematicallyillustrates exemplary features that can be provided in a container 320so as to tag that container and acoustically characterize the containerin a manner such as described herein with reference to FIG. 2, accordingto some embodiments of the present invention. More specifically, FIG. 3illustrates an exemplary embodiment for patterning digital informationin a container 320, outside the acoustic path of ADE. The zoomed-ininsets of FIG. 3 (A-D) illustrate examples of how digital features of atag can be patterned along the periphery of an acoustic container 320,or near a well in a multi-well plate 320 (side view of the container inA-C; bottom view in D). The graphs below the respective insets show anidealized interpretation of the returning acoustic time-of-flight (ToF)signal. In some embodiments, the features of the tag suitably canaccommodate one or more ADE design constraints, such as reducing oravoiding sharp corners to reduce or inhibit fluid pinning, or can be ofappropriate size so as to maintain coupling of the fluid and thecontainer while allowing for drying operations. In some embodiments, thepattern can be one-dimensional (1-D), e.g., as shown in FIG. 3, so as tobe read during translation from one tube to the next along a line. Inother embodiments, the pattern can be two-dimensional (2-D), where thesecond dimension is along the transducer's major axis, or along the axisperpendicular to the translational axis shown in FIG. 3 (e.g., in andout of the page). Inset A in FIG. 3 illustrates an exemplary embodimentin which bits can be coded along the transducer 310 major axis. Inset Bin FIG. 3 illustrates an embodiment in which bits can be encoded byvarying one of the x-y translational axis. Note that other suitablecombinations of such features readily can be envisioned, such asproviding unique aspect ratios along the translational axis.Additionally, although insets A and B of FIG. 3 show recessed featuresof the tag, the features instead suitably can protrude from the bottomof the part 320 or can be recessed within the part 320; or somecombination of the two conditions or configurations. For example, insetC illustrates an embodiment in which bits are encoded with raisedfeatures, rather than recessed features.

The acoustic signal obtained from parts 320 such as illustrated in FIG.3 can include the ToF of the acoustic signal from the bottom-bottom (BB)of the part 320 (e.g., bottom 222 of bottom 221 (BB) of tube orcontainer 220 such as described herein with reference to FIG. 2)—e.g.,the total time from when the acoustic signal initially was launched towhen the reflected acoustic signal returns to the transducer 310. Twodifferent ToF values can be received by the transducer 310, with one ToFrepresenting “1” (corresponding to the deeper recesses in the tag) andanother ToF value representing a “0” (corresponding to the shallowerrecesses in the tag). The pattern of “bits” can be 1-D, which canprovide information relatively quickly and can be rotationally redundantwithout the need for alignment; or can be 2-D, e.g., so as to implementx-y grid surveys, which potentially can provide greater informationdensity but potentially can be slower to execute. A liquid handler canreliably resolve small changes in the ToF detected by the transducer310. For example, features that vary by tens of microns in depth fromone another can produce ToFs that can be distinguished reliably by aliquid handler using either 5 to 10 MHz for the acoustic detectionpulse. Greater sensitivity can be achieved by using higher soundfrequencies and optimizing focus on the features to be measured. In someembodiments, the returning acoustic signals can include absolute values,such as unique ToFs for 0's and 1's, or can be related to anotheracoustic signal on the part, such as the ToF in the non-patternedportion of the part or within the patterns themselves.

One non-limiting example of this embodiment includes 64 unique patternson or within the container-bottom and arranged in a bit-wise patterningscheme including 6 unique bits that respectively correspond either to 1or 0. In this example, each bit can be discernible as a 1 or 0 by theacoustic transducer. Note that other suitable combinations of suchfeatures readily can be envisioned, such as providing unique aspectratios along the translational axis so that each feature provided morethan one bit of information. Such embodiments are broadly extendible toa variety of geometric patterns and dimensions and can be optimized byone of skill in the art based on the teachings provided herein.

Exemplary Embodiment 2: Dimples that Change in Length, Aspect Ratio, orDepth

In another non-limiting embodiment of the invention, the present tagscan convey still further information by utilizing 3-D patterning, e.g.,in which length, aspect ratio, depth, frequency, or any other geometricfeature of the pattern suitably can be selected so as to uniquely encodeinformation from the mold location onto the part. Such embodiments canbe higher-resolution than certain 1-D or 2-D embodiments because thefeatures can be considered to be more “analog” in nature rather thanbeing converted to l's and 0's.

For example, FIG. 4 schematically illustrates exemplary features thatcan be provided in a container 420 so as to tag that container andacoustically characterize the container in a manner such as describedherein with reference to FIG. 2, according to some embodiments of thepresent invention. The graph below the features show an idealizedinterpretation of the returning acoustic ToF signal. More specifically,FIG. 4 illustrates a non-limiting embodiment of a pattern of uniqueshapes and geometries outside the acoustic path of ADE in a more“analog” type format, in which the magnitude and shape of the featuresto be read are tied to the respective location within the mold. Allthree dimensions, the two x- and y-translational axes and the transducer410 z-axis, can be used for encoding information (e.g., in the form offeatures of a tag). Notice that the BB ToF varies in magnitude (heightof each peak in the graph), and duration as the transducer scans thefeatures (width of each peak). One exemplary feature of such a scheme isthat more complex information can be stored within a given amount ofspace.

In one example, based upon the acoustic system being capable ofresolving depth differentials of features at 10 micron resolution andfour possible feature depths being used with each 20 microns deeper thanthe next, then 2 bits can be encoded with features in which the largestand smallest feature depths differ from one another by 60 microns.Larger depth ranges or finer step sizes suitably can be used based onthe container dimensions, acoustic frequencies, container material(s),and the like.

Exemplary Embodiment 3: Superhydrophobic Design Features that Introducean Air Gap

In another non-limiting embodiment, an alternative readout method to theBB ToF is to utilize the voltage returned from the BB acousticreflection (BB peak-to-peak voltage, or BB Vpp). The pattern imparted onthe part (e.g., container) can include one or more superhydrophobicfeatures, such as a micropillar array, that intentionally introduce oneor more air gaps at the coupling fluid-plastic interface so as to returna higher acoustic signal voltage than regions where sound is moreuniformly transmitted through the plastic (e.g., no air gap between thecoupling fluid and the plastic). Such air gaps can be patterned in adigital, l's and 0's, format in a manner similar to that described abovewith reference to exemplary embodiment 1; or such air gaps can bepatterned in 1-D or 2-D analog formats in a manner similar to thatdescribed above with reference to exemplary embodiment 2; the thirddepth dimension optionally can be used, for example, in embodiments inwhich BB ToF is simultaneously considered, or BB Vpp is adequatelyresolved as a function of distance along the depth dimension. Exemplaryfeatures of such embodiments can include one or more of: increasedsensitivity in acoustically reading the BB Vpp, and to relativelystraightforward management strategies of the coupling fluid-plasticinteraction.

For example, FIG. 5 schematically illustrates exemplary features thatcan be provided in a container 520 so as to tag that container andacoustically characterize the container in a manner such as describedherein with reference to FIG. 2, according to some embodiments of thepresent invention. More specifically, FIG. 5 illustrates non-limitingexamples of embodiments in which a tag includes hydrophobic featuresprovided outside the acoustic path of ADE, e.g., in which air-containingbreaks between the coupling fluid and plastic of the part (e.g.,container) are introduced so as to increase reflection of the acousticsignal to the transducer 510. In some embodiments, such breaks can beprovided by patterning hydrophobic features, such as a micropillararray, into the plastic of the container. The graphs below the insetsshow the voltage increasing at the fluid-air interface, which can beread instead of the ToF. Inset A illustrated in FIG. 5 shows anexemplary embodiment that includes recessed notches that intentionaldecouple the coupling fluid from the plastic. Inset B illustrated inFIG. 5 shows an exemplary embodiment that includes an “analog” typeencoding scheme using similar features. Inset C illustrated in FIG. 5shows an exemplary embodiment that includes digital patterning usingraised hydrophobic features. Note that although the non-limitingembodiments of in insets A-C are illustrated as including relativelysharp edges, such edges instead can be curved and otherwise suitablyshaped so as to reduce or inhibit fluid pinning.

Exemplary Embodiment 4: Variations in Thickness of the Plastic in thePath of Acoustic Beam

In another embodiment, the tag (e.g., feature that identifies a moldlocation) can be located at the interface between the container and thefluid disposed therein, or the top of the bottom (TB) of the part. Forexample, the difference in ToF between the TB and BB acoustic signals(divided by two), represents the total time the acoustic signal takes tomove through the part or container bottom, e.g., plastic, one-way. Sucha difference in ToF (divided by two) can be converted to a membranethickness—the thickness of the bottom of part (e.g., acoustic tube) thatis an intermediary between the coupling fluid and the fluid within thecontainer. The membrane thickness of the part suitably can be varied soas to resolve the membrane thickness differences that are intentionallyintroduced in parts from different locations within the mold.Alternatively, just the BB ToF (BB distance to the transducer) can alsobe varied so as to change the membrane thickness of the part. In someembodiments, only a single acoustic signal can be used so as to obtainsuch a difference in ToF, although more than one acoustic signalsuitably can be used. Note that the membrane optionally can be in theacoustic path of ADE.

For example, FIG. 6 schematically illustrates exemplary features thatcan be provided in a container 620 so as to tag that container andacoustically characterize the container in a manner such as describedherein with reference to FIG. 2, according to some embodiments of thepresent invention. More specifically, FIG. 6 illustrates an embodimentthat includes patterning variable membrane thicknesses (optionally)within the acoustic path of ADE, and in which the membrane thickness,e.g., the differential distance of BB and TB from the transducer 610,can be varied between parts so as to identify the well's location withinthe mold. For example, a unique membrane thickness can be assigned toeach part within the mold/cavity such that the parts are acousticallydistinguishable from one another. The graphs below the respective insetsshow an idealized interpretation of the returning acoustictime-of-flight ToF signal. Inset A illustrated in FIG. 6 shows oneexemplary embodiment in which the TB ToF is varied. Inset B illustratedin FIG. 6 shows another exemplary embodiment in which the BB ToF isvaried. Inset C illustrated in FIG. 6 shows another exemplary embodimentin which the TB ToF is made taller (thicker) such that the acousticsignal recognition used to characterize the fluid and perform ADE stillfunctions properly.

Exemplary Embodiment 5: Exemplary Features that Utilize Mound ImagingAlgorithms with One or More Null Space Solutions

In another non-limiting embodiment, an alternative readout method can beused that examines the returning complex frequency content of anacoustic signal interacting with a uniquely shaped dimple in theplastic. For example, FIG. 7 schematically illustrates exemplaryfeatures that can be provided in a container 720 so as to tag thatcontainer and acoustically characterize the container in a manner suchas described herein with reference to FIG. 2, according to someembodiments of the present invention. More specifically, FIG. 7illustrates that acoustic characteristics of a fluid can be determinedby examining the complex frequency content of the returning acousticsignal after a “mound” has been formed on the fluid surface. The shapeof the mound can create unique acoustic signals that can be interpretedso as to identify the “null spacing” of the signals (targeted minima inthe Fourier-space of the acoustic signal). In some embodiments, dimplesof particular diameter (or ellipsoidal), depth, and shape can beindented outside of the acoustic ejection window so as to create nullspace identifiers that are unique to the location of the mold. Suchembodiments can represent a more analog method of conveying theinformation, which has the advantage of needing fewer features on thepart.

For example, in one non-limiting embodiment, a system for characterizinga container configured to hold a fluid can include the container, thecontainer including at least one vertical sidewall; and a bottom coupledto the at least one vertical sidewall, the bottom being configured toreceive an acoustic signal, the bottom including a thickness that variesalong a lateral dimension. The system also can include an acoustictransducer configured so as to transmit an acoustic signal through thebottom, the varying thickness providing a plurality of times of flightof the acoustic signal through the bottom. The acoustic transducerfurther can be configured so as to receive a reflection of thetransmitted acoustic signal. The system further can include acontroller, such as a computer and associated software algorithms,configured so as to characterize an acoustic impedance of the containerbased on the reflection.

In another non-limiting embodiment, a method of characterizing acontainer configured to hold a fluid, can include providing such acontainer; transmitting an acoustic signal through the bottom, thevarying thickness providing a plurality of times of flight of theacoustic signal through the bottom; receiving a reflection of thetransmitted acoustic signal; and characterizing an acoustic impedance ofthe container based on the reflection.

Exemplary Embodiment 6: Exemplary Features that Utilize Overmolding ofMultiple Materials to Vary the Acoustic Impedance

In another non-limiting embodiment, an alternative encoding method canbe utilized, whereby the identifying features are distinguished from theprimary container by overmolding one or more additional materials(non-limiting examples include polymers, metals, and ceramics), withacoustically distinguishable impedance value(s) compared to that of thecontainer, to the pattern mold- or cavity-specific identifiers. In suchembodiments, the distinguishing features can exhibit different BBvoltage values (similar to embodiment 3), which can facilitate thepattern to be resolved acoustically by the transducer.

Exemplary Embodiments

In one non-limiting example, a container configured to hold a fluidincludes at least one vertical sidewall; and a bottom coupled to the atleast one vertical sidewall, the bottom being configured to receive anacoustic signal, the bottom including a plurality of recesses, grooves,or protrusions thereon or therein so as to provide a plurality of timesof flight of the acoustic signal through the bottom. Examples of suchcontainers are provided herein, e.g., with reference to FIGS. 2, 3, 4,5, and 7.

In some embodiments, a first subset of the plurality of recesses,grooves, or protrusions includes a first depth providing a first time offlight of the acoustic signal, and a second subset of the plurality ofrecesses, grooves or protrusions includes a second depth providing asecond time of flight of the acoustic signal, the first depth beingdifferent from the second depth.

In some embodiments, a first one of the plurality of recesses, grooves,or protrusions includes a different length, aspect ratio, or depth thana second one of the plurality of recesses, grooves, or protrusions.

In some embodiments, the plurality of recesses, grooves, or protrusionsinclude a hydrophobic region configured so as to increase or decreasethe amplitude of reflection of the acoustic signal. For example, in someembodiments, the plurality of recesses, grooves, or protrusions includea hydrophobic micropillar array.

In some embodiments, the plurality of recesses, grooves, or protrusionsare configured so as to be located outside of an acoustic path betweenthe fluid and an acoustic transducer generating the acoustic signal. Insome embodiments, the plurality of recesses, grooves, or protrusions areconfigured so as to be located along and within an acoustic path betweenthe fluid and an acoustic transducer generating the acoustic signal.

In some embodiments, the container includes a multiwell plate, avertical sidewall of the at least one vertical sidewall and the bottomcorresponding to a single well of the multiwall plate.

In some embodiments, the sidewall and the bottom include a plastic. Insome embodiments, the plastic is selected from the group consisting ofcyclic olefin polymer, cyclic olefin copolymer, polypropylene, andpolystyrene.

Under another aspect, a container configured to hold a fluid includes atleast one vertical sidewall; and a bottom coupled to the at least onevertical sidewall, the bottom being configured to receive an acousticsignal, the bottom including a thickness selected such that thecontainer is identifiable based on a time of flight of the acousticsignal through the bottom. Examples of such containers are providedherein, e.g., with reference to FIG. 6.

Under yet another aspect, a method of characterizing a containerconfigured to hold a fluid includes providing the container. Thecontainer can include at least one vertical sidewall; and a bottomcoupled to the at least one vertical sidewall, the bottom beingconfigured to receive an acoustic signal, the bottom including aplurality of recesses, grooves, or protrusions thereon or therein. Themethod can include transmitting an acoustic signal through the bottom,the plurality of recesses, grooves, or protrusions providing a pluralityof times of flight of the acoustic signal through the bottom. The methodalso can include receiving a reflection of the transmitted acousticsignal; and characterizing an acoustic impedance of the container basedon the reflection. Examples of such a method are provided herein, e.g.,with reference to FIGS. 2, 3, 4, 5, and 7.

In some embodiments, the method includes retrieving from acomputer-readable medium a value characterizing a thickness of thebottom based on the reflection. The characterizing the acousticimpedance of the container can be based on the retrieved valuecharacterizing the thickness of the bottom.

In some embodiments, a first subset of the plurality of recesses,grooves, or protrusions includes a first depth providing a first time offlight of the acoustic signal, and a second subset of the plurality ofrecesses, grooves or protrusions includes a second depth providing asecond time of flight of the acoustic signal, the first depth beingdifferent from the second depth.

In some embodiments, a first one of the plurality of recesses, grooves,or protrusions includes a different length, aspect ratio, or depth thana second one of the plurality of recesses, grooves, or protrusions.

In some embodiments, the plurality of recesses, grooves, or protrusionsinclude a hydrophobic region configured so as to increase reflection ofthe acoustic signal. For example, in some embodiments, the plurality ofrecesses, grooves, or protrusions include a hydrophobic micropillararray.

In some embodiments, the plurality of recesses, grooves, or protrusionsare located outside of an acoustic path between the fluid and anacoustic transducer generating the acoustic signal. In some embodiments,the plurality of recesses, grooves, or protrusions are located along andwithin an acoustic path between the fluid and an acoustic transducergenerating the acoustic signal.

In some embodiments, the container includes a multiwell plate, and avertical sidewall of the at least one vertical sidewall and the bottomcorrespond to a single well of the multiwall plate.

In some embodiments, the sidewall and the bottom include a plastic. Insome embodiments, the plastic is selected from the group consisting ofcyclic olefin polymer, cyclic olefin copolymer, polypropylene, andpolystyrene.

Under another aspect, a method of characterizing a container configuredto hold a fluid includes providing the container. The container caninclude at least one vertical sidewall; and a bottom coupled to the atleast one vertical sidewall, the bottom being configured to receive anacoustic signal, the bottom including a thickness. The method caninclude receiving a reflection of the transmitted acoustic signal, thereflection having a time of flight through the thickness; identifyingthe container based on the time of flight; and characterizing anacoustic impedance of the container based on the identification. Anexample of such a method is provided herein, e.g., with reference toFIG. 6.

Under still another aspect, a system for characterizing a containerconfigured to hold a fluid includes the container. The container caninclude at least one vertical sidewall; and a bottom coupled to the atleast one vertical sidewall, the bottom being configured to receive anacoustic signal, the bottom including a plurality of recesses, grooves,or protrusions thereon or therein. The system also can include anacoustic transducer configured so as to transmit an acoustic signalthrough the bottom, the plurality of recesses, grooves, or protrusionsproviding a plurality of times of flight of the acoustic signal throughthe bottom. The acoustic transducer further can be configured so as toreceive a reflection of the transmitted acoustic signal. The systemfurther can include a controller configured so as to characterize anacoustic impedance of the container based on the reflection. Examples ofsuch a system are provided herein, e.g., with reference to FIGS. 2, 3,4, 5, and 7.

In some embodiments, the system further includes a computer-readablemedium. The controller can be configured so as to: retrieve from thecomputer-readable medium a value characterizing a thickness of thebottom based on the reflection; and characterize the acoustic impedanceof the container based on the value characterizing the thickness of thebottom.

In some embodiments, a first subset of the plurality of recesses,grooves, or protrusions includes a first depth providing a first time offlight of the acoustic signal, and a second subset of the plurality ofrecesses, grooves or protrusions includes a second depth providing asecond time of flight of the acoustic signal, the first depth beingdifferent from the second depth.

In some embodiments, a first one of the plurality of recesses, grooves,or protrusions includes a different length, aspect ratio, or depth thana second one of the plurality of recesses, grooves, or protrusions.

In some embodiments, the plurality of recesses, grooves, or protrusionsinclude a hydrophobic region configured so as to increase reflection ofthe acoustic signal. For example, in some embodiments, the plurality ofrecesses, grooves, or protrusions include a hydrophobic micropillararray.

In some embodiments, the plurality of recesses, grooves, or protrusionsare located outside of an acoustic path between the fluid and anacoustic transducer generating the acoustic signal. In some embodiments,the plurality of recesses, grooves, or protrusions are located along andwithin an acoustic path between the fluid and an acoustic transducergenerating the acoustic signal.

In some embodiments, the container includes a multiwell plate, avertical sidewall of the at least one vertical sidewall and the bottomcorresponding to a single well of the multiwall plate.

In some embodiments, the sidewall and the bottom include a plastic. Insome embodiments, the plastic can be selected from the group consistingof cyclic olefin polymer, cyclic olefin copolymer, polypropylene, andpolystyrene.

Under yet another aspect, a system for characterizing a containerconfigured to hold a fluid includes the container. The container caninclude at least one vertical sidewall; and a bottom coupled to the atleast one vertical sidewall, the bottom being configured to receive anacoustic signal, the bottom including a thickness. The system caninclude an acoustic transducer configured so as to transmit an acousticsignal through the bottom. The acoustic transducer further can beconfigured so as to receive a reflection of the transmitted acousticsignal, the reflection having a time of flight through the thickness.The system further can include a controller configured so as to:identify the container based on the time of flight; and characterize anacoustic impedance of the container based on the identification.Examples of such a system are provided herein, e.g., with reference toFIG. 6.

Other Alternative Embodiments

Although specific embodiments of the present invention have beendescribed, it will be understood by those of skill in the art that thereare other embodiments that are equivalent to the described embodiments.Accordingly, it is to be understood that the invention is not to belimited by the specific illustrated embodiments, but only by the scopeof the appended claims.

1.-11. (canceled)
 12. A method of characterizing a container configuredto hold a fluid, the method comprising: providing the container, thecontainer comprising: at least one vertical sidewall; and a bottomcoupled to the at least one vertical sidewall, the bottom beingconfigured to receive an acoustic signal, the bottom including aplurality of recesses, grooves, or protrusions thereon or therein;transmitting an acoustic signal through the bottom, the plurality ofrecesses, grooves, or protrusions providing a plurality of times offlight of the acoustic signal through the bottom; receiving a reflectionof the transmitted acoustic signal; and characterizing an acousticimpedance of the container based on the reflection.
 13. The method ofclaim 12, further comprising: retrieving from a computer-readable mediuma value characterizing a thickness of the bottom based on thereflection; and wherein the characterizing the acoustic impedance of thecontainer is based on the retrieved value characterizing the thicknessof the bottom.
 14. The method of claim 12, wherein a first subset of theplurality of recesses, grooves, or protrusions includes a first depthproviding a first time of flight of the acoustic signal, and wherein asecond subset of the plurality of recesses, grooves or protrusionsincludes a second depth providing a second time of flight of theacoustic signal, the first depth being different from the second depth.15. The method of claim 12, wherein a first one of the plurality ofrecesses, grooves, or protrusions includes a different length, aspectratio, or depth than a second one of the plurality of recesses, grooves,or protrusions.
 16. (canceled)
 17. The method of claim 15, wherein theplurality of recesses, grooves, or protrusions include a hydrophobicmicropillar array.
 18. The method of claim 12, wherein the plurality ofrecesses, grooves, or protrusions are located outside of an acousticpath between the fluid and an acoustic transducer generating theacoustic signal.
 19. The method of claim 12, wherein the plurality ofrecesses, grooves, or protrusions are located along and within anacoustic path between the fluid and an acoustic transducer generatingthe acoustic signal.
 20. The method of claim 12, wherein the containerincludes a multiwell plate, and a vertical sidewall of the at least onevertical sidewall and the bottom correspond to a single well of themultiwall plate.
 21. The method of claim 12, wherein the sidewall andthe bottom include a plastic.
 22. The method of claim 21, wherein theplastic is selected from the group consisting of cyclic olefin polymer,cyclic olefin copolymer, polypropylene, and polystyrene. 23.-35.(canceled)
 36. A method for characterizing a fluid within a containerconfigured to hold the fluid, the method comprising: providing acontainer holding a first fluid, the container including: at least onevertical sidewall; and a bottom connected to the at least one verticalsidewall, the bottom being at least partially coupled to a couplingfluid; sending a first acoustic signal to the bottom of the container,the bottom configured to provide a plurality of times of flight of thefirst acoustic signal; receiving a first reflection of the firstacoustic signal; characterizing a first acoustic impedance of thecontainer based at least in part on the first reflection of the firstacoustic signal; sending a second acoustic signal to the bottom of thecontainer and the first fluid through the coupling fluid; receiving asecond reflection of the second acoustic signal through the couplingfluid; characterizing a second acoustic impedance of the first fluidbased at least in part on the first acoustic impedance of the containerand the second reflection of the second acoustic signal; obtaining oneor more parameters for an acoustic droplet ejection based at least inpart on the second acoustic impedance of the first fluid; and performingthe acoustic droplet ejection based at least in part on the obtained oneor more parameters.
 37. A method for characterizing a fluid within acontainer configured to hold the fluid, the method comprising: providinga container holding a first fluid, the container including: at least onevertical sidewall; and a bottom connected to the at least one verticalsidewall, the bottom being at least partially coupled to a couplingfluid; sending a first acoustic signal to the bottom of the container,the bottom configured to provide a plurality of times of flight of thefirst acoustic signal; receiving a first reflection of the firstacoustic signal; characterizing a first acoustic impedance of thecontainer based at least in part on the first reflection of the firstacoustic signal; sending a second acoustic signal to the bottom of thecontainer and the first fluid through the coupling fluid; receiving asecond reflection of the second acoustic signal through the couplingfluid; characterizing a second acoustic impedance of the first fluidbased at least in part on the first acoustic impedance of the containerand the second reflection of the second acoustic signal; obtaining oneor more parameters for the first fluid based at least in part on thesecond acoustic impedance of the first fluid; and outputting theobtained one or more parameters for the first fluid.